I found this Indian set, including its brownish accessories, in an antique shop in 1998. It looks like a near perfect match to the Indian Warrior set shown in Breyer's 1958 catalog. (Notice the war paint running down his arms, and the fact that there is no colorful trim on his breechcloth or on the fringes running down the side of his leggings.) However that 1958 catalog does not list a headdress as an included accessory, but this plastic war bonnet was on the Indian when I found it. It was the only horse & rider in that dealer's booth; they apparently had no clue that it was a Breyer product; and since it had so many other correct accessories (arrow, quiver, knife, tomahawk and blanket) I believe it to be a well-cared-for, intact set. Thus, I believe the war bonnet (headdress) to be original to this set as well.
As a side note, the Robin Hood set pictured in the 1958 catalog has only a sword, no bow. So, were those late '50s sets sold with fewer accessories, or was it a simple case of the catalog not showing all the accessories that would be included?